Significant benefits can be derived from the ability to grow cells in vitro on biodegradable supports or scaffolds followed by transplantation to a human needing cells for tissue repair or replacement. Cells that could be grown for such tissue engineering include osteoblasts for new bone, chondrocytes for cartilage, fibroblasts for dermal tissue and retinal pigment epithelial cells (RPE) for the eye.
Some research regarding this aspect of tissue engineering has already been reported. For example, Mikos et al, have prepared poly(glycolic acid) bonded fiber structures for cell attachment and transplantation. J. of Biomedical Materials Research, Vol. 27, 183-189 (1993). Their preparations involved formation of a composite material between poly(glycolic acid) nonwoven fiber meshes and poly(L-lactic acid) (PLLA) followed by thermal treatment and selective dissolution of the PLLA matrix. Others have investigated porous sheets of polymer for such cell growth. Although the growth of cells on such porous film has been demonstrated, there are difficulties with such an approach.
The task of tissue engineering is complicated by the need of most cells to have special surfaces for attachment, proliferation and cell interactions. Additionally, some cells have distinctly different basal and apical characteristics and are polar in nature so that they function properly only when they are properly oriented.
There is a need, therefore, for a technique to develop and grow cells in vitro in a manner such that they will function properly when implanted. To this end, biodegradable polymers are needed to act as a scaffold or support for the development and growth of such cells. The scaffold should allow the growing cells to organize and develop special cellular function such as cell attachment, proliferation and maintenance of distinct basal and apical characteristics.